This proposal is designed to study the mechanisms of the cellular regulation of mRNA transcription, processing and cytoplasmic utilization in tissue culture cells and developing embryos of Drosophila melanogaster. These experiments may be applied to the elucidation of the regulation of development and the fundamental problems will consist of an investigation of the role of non-histone poly(A) minus mRNA and its relationship to poly(A) plus mRNA. My specific objectives are to:(a) Determine the number and kinds of proteins made by the poly(A) minus mRNA from tissue culture cells. This message will be translated in a cell free system and the products analyzed on gels and in reconstitution experiments with appropriate cell fractions. (b) Analyze the kinds of DNA sequences which code for poly(A) minus mRNA. Labeled radioactive RNA from tissue culture cells will be hydridized to DNA in vast DNA excess. (c) Determine the number of sequences and their abundancies in the poly(A) minus mRNA population. A complementary copy of the poly(A) minus molecules will be synthesized by affixing a string of nucleotides to the 3' end. The mRNA will be copied with an RNA dependent DNA polymerase. The labeled complementary DNA will be hybridized with the RNA. (d) Investigate the role of cytoplasmic adenylation in mRNA utilization during the development of Drosophila embryos. It will be determined if adenylation of pre-existing mRNA's occurs after fertilization. It is important to determine if there is poly(A) minus mRNA in eggs and whether any is newly synthesized.